1. Field of the Invention
The present invention relates generally to electronic power supplies, and more specifically to optimizing the operation of redundant power supply systems.
2. Background of the Related Art
A computer system is typically powered by one or more electrical power supplies intended to provide a continuous supply of power. An electronic power supply converts electricity from an electrical power source, such as an alternating current power outlet, to a form usable by a computer system and its various components. For example, a power supply may convert alternating current (AC) to direct current (DC) having a DC voltage specified by the computer system to be powered.
Redundant power supplies are provided in many computer systems to increase reliability of operation. If one power supply fails, another power supply is then available to compensate for the failed power supply. A simple system may, for example, provide “N+N” redundancy, where a number (N) of computer systems are each provided with a number (N) of primary power supplies and a number (N) of redundant power supplies.
A power supply typically has fixed power losses that result in an improved efficiency at higher system loading. When two or more power supplies of a redundant system are operated in parallel to share a system load, the power supplies will be operating at a lower point on their respective efficiency curves. To improve the efficiency of redundant systems, one approach has been to shut down one or more of the redundant power supply units or place them in a standby mode until needed, so that the remaining power supply(ies) operate at a higher efficiency.